I've ripped my first Blu-ray into 13 .m2ts files.... I could use the files straight up in my editing program, but I'm used to converting them into a different format first before editing so I can pull clips from it. Should I go ahead and use the m2ts files straight up, or should I convert them first before making clips from them?

~BRAKUS~Otakon AMV Theater staff, AWA AMV VAT staff"Whatever you do, enjoy it to the fullest. That is the secret of life."-- Rider (Iskander), Fate/Zero

You should definitely convert the m2ts files first. I personally recommend making lossless clips with virtualdub, possibly using utvideo as the codec. Editing m2ts directly is not advised because they aren't the lightest thing to decode, especially if you'll need to put clips in reverse time. That is going to kill your pc quite easily...

Yes, that is indeed correct. The best solution for loading the m2ts in avisynth is dgdecnv, or alternatively dgavcdecdi, but they aren't free solutions.A free solution involves remuxing to mkv and then using ffvideosource, but keep in mind that this latter method doesn't always work, you won't be able to make clips right off as you should be transcoding it all to lossless first and then clipping/filtering from there to play it safe.